package leetcode;

public class _0141 {
    /**
     *环形链表
     */
    /**
     * Definition for singly-linked list.
     * class ListNode {
     *     int val;
     *     ListNode next;
     *     ListNode(int x) {
     *         val = x;
     *         next = null;
     *     }
     * }
     */
    public class Solution {
        public boolean hasCycle(ListNode head) {
            ListNode slow = head,fast = head;
            while(fast!=null&&fast.next!=null){
                slow = slow.next;
                fast = fast.next.next;
                if(slow==fast){
                    return true;
                }
            }
            return false;
        }
    }
    private class ListNode {
        ListNode next;
        int val;
        ListNode(){}
        ListNode(int val){
            this.val=val;
        }
        ListNode(int val, ListNode next){
            this.val = val;
            this.next = next;
        }
    }
}
